Water treated shadowmarks



Dec- 30, 1969 B. D. sKoFRoNlcK WATER TREATED SHDOW'MARKS Fild Feb. 21, 1968 13 L B. PAPER l l l 5 lo l5 wasn Telnr Mams u. mwmsosm..

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k t w 28 LB. PAPER EigA- 24L PAPER WATER TREATMENTS 5 lo INA-ren TREATMENTS Irivlen'kor Bruce D. Skofrorzick 1% w/ fdr/er United States Patent O U.S. Cl. 117-37 2S Claims ABSTRACT OF THE DISCLOSURE A paper article is made opaque relative to the original light transmission properties of the paper. The opaque area may extend throughout the entire sheet or may be a limited area of a selected design to obtain a shadowmark. The opaque area is obtained by applying a resin to a paper area and then contacting the area with water. The opaque area is raised relative to the original thickness of the paper. The paper articles are made by applying a liquid composition to the surface of a sheet of paper. The liquid composition includes a resin which can be laid down as a wet lm and which will impregnate paper fibers or the paper web. The resin is applied to the surface of paper to opacify the entire paper or a limited area to provide a shadowmark. While one water treatment step may be sufficient for some embodiments, it is provided that other embodiments may require a plurality of successive Water treatment and intervening drying steps to develop or enhance the development of the opaque area.

This application and the invention herein is a continuation-in-part of U.S. patent applications Ser. No. 525,343 filed Feb. 7, 1966, and Ser. No. 536,487 now abandoned, filed Feb. 7, 1966, Ser. No. 699,688 now abondoned, tiled Jan. 22, 1968, and Ser. No. 699,664 allowed filed Jan. 22, 1968.

This invention relates to a paper article having 'areas more opaque than the original paper, and it also relates to a method for opacifying areas.

It is now known in the art to prepare sheets of paper having areas which are rendered translucent in whole or in part by contacting the sheets of paper with chemical impregnating materials. See, for example, U.S. Letters Patent Numbers 3,293,062; 3,140,959 and 3,085,898.

The liquid resin compositions are applied to the surface of the paper, and the resin is then hardened r dried, limited only to a portion of the surface area, and when a whereupon a translucent area is obtained. When the area is limited only to a portion of the surface area, and when a fanciful design is formed, then the translucent area may be considered as being a watermark. Such a watermark may appear to be of the same quality as conventional watermarks, and they may also be referred to as simulated watermarks or chemical watermarks. This is a recognized advance in the paper art because high quality watermarks are obtained which have economic advantages as a result of the substantially lower costs incurred in producing the marks. Such marks may be applied or printed on paper in smaller runs after the paper is formed. This is in contradistinction to the conventional watermarks which are made by a dandy roll during the paper forming stage.

shadowmarks are formed in paper sheets for the same 3,486,923 Patented Dec. 30, 1969 Mice general purposes as are watermarks, that is, for reasons of quality, identification, esthetics and the like. The conventional shadowmarks are opaque relative to the balance of the paper as distinguished from watermarks which are translucent relative thereto. Up to the`time of the present invention, shadowmarks have been formed by a dandy roll during a paper making stage. Watermarks have been formed by a raised die on the dandy roll spreading paper fibers, whereas shadowmarks have been formed by a recess or well in the dandy roll in which the paper fibers collect.

For the same desirable reasons of economy, as well as simplicity and still other reasons, the art 'would welcome a simple chemical method by which shadowmarks could be formed on sheets of paper.

It is therefore one important object of the present invention to provide la novel paper article in which areas are made opaque relative to the original condition of the paper by readily available materials. A feature of this object is the attainment of opaque areas on paper which are serviceable in the sense of substantial permanency, receptivity to writing or printing, freedom froml discoloration, and other properties which are desirable for paper as such.

Another important object of this invention is a paper sheet on which shadowmarks of Varying design may be formed by the simple step of applying a liquid composi-` tion to the surface of the paper in a selected design, and then treating the applied liquid composition by one or more following steps which are simple and economical.

Yet another important object of this invention is a method by which paper sheets may be entirely opacified by applying a liquid composition to the sheet to impregnate the paper fibers with a resin and then inducing the formation of a plurality of interfaces in the deposited resin -to render such resin-deposited areas opaque relative to the original light transmission of the paper.

A similar and important object of this invention is to make shadowmarks on sheets of paper by the same general procedure as suggested in the preceding object.

Yet another important object of this invention is a new paper article, with opaque areas, yand methods for preparing such an article which allows the use of a wide variety of available resin materials which can be laid down as a wet lm and which can impregnate the paper fibers or paper web. A desired feature of this lobject are process steps Which allow Various means to be successfully used in the method.

The foregoing objects are realized as well as still other objects which will occur to practitioners from considering the invention described and claimed in the following disclosure, which also includes drawings wherein FIGURES 1-6 illustrate how capacity of paper is increased in accordance with the teachings of `the invention.

This invention provides that opaque areas are made on paperl by applying a liquid composition containing one or more resins to the surface of the paper so that the resin islaid down as a wet film and irnpregnates the paper fibers or the paper web. The composition is in a 'liquid form to facilitate application, and has a viscosity which is sufficiently low to allow the desired impregnation. When opacifying entire sheets of paper, it is only required that the viscosity be not so excessively low so that the impregnating composition would pass through the paper. When making opaque shadowmarks, the viscosity is sufficiently high to retain the design which has been applied to the surface of the paper. In other words, 'the'vi'scosity' is low enough to impregnate, but not low enough to distort the preselected design which has been applied to the surface.

The liquid resin film or layers which have been ap- -plied to the surface of the paper are then rendered more opaque than the original paper by contacting such resin with water. This step leads to attaining an opaque area which is further raised relative to the original surface of the paper.

Such results would not occur without the water treatment. In fact, without water treatment the area would become translucent relative to the original condition of light transmission, and the area would not be essentially lraisedrelative to the original surface of the paper.

In some instances, a single water treatment step will lead to forming an opaque area but, in many instances, this will not lead to a desirably formed opacity. It has likewise been discovered that a plurality of successive water treatment and intervening drying steps can lead to the development of an opaque area, or to the forma'- tion of better defined opacity.

It is not known with certainty how the resi'n of the liquid composition has been altered by the water contact, but the area does become raised and does exhibit a recognizable lessening or lowering of light transmission. It is clear that a plurality of interfaces are formed in such an opaque area because the area is raised and because the light transmission has been significantly changed relative to the original light transmission of the original paper. These interfaces may be voids or waterresin interfaces or modified resin interfaces or what have you. Without intending any particular identification or characterization; it is nonetheless accurate and meaningful to refe'r to a plurality of such interfaces in the dried or hardened resin which renders the resin opaque and raised relative to the original paper.

Some sort of incompatability may result between the resin and water following one or more steps of contacting the resin with the water. The presence of the water is believed to directly participate in the development of opacity to measurable or recognizable levels following a plurality of successive water treatment and drying steps. The water may be functioning in conjunction with a subsequent heating step. Be that as it may, the practitioner who follows the teachings of this disclosure will readily'recognize when an opaque area is formed after one or after a plurality of successive wetting and drying steps.

The use of the term liquid composition will refer to the entire liquid body which is handled and applied to the surface of a sheet of paper. Such a composition need only be liquid so that it may be conveniently applied either to the entire sheet or to a limited area to form Ia shadowmark.

`When reference is made to impregnating paper fibers or -paper web it is intended to mean that the resin moves between the paper fibers or into the paper fibers, or both. The important point is that the resin should not conglomerate or puddle on the surface of the paper because an undesirable quality of shadowmark, if any, would resultv with respect to permanency, appearance and 'serviceability. It is not known certainly how much of the resin actually penetrates into the fibers or merely collects between fibers.

-The liquid composition may consist of a resin alone which is in fluid form, or it may include a mixture of resins-'to effect greater fluidity, for example, it may include'a plasticizer which acts as a diluent. The liquid composition may also contain an organic solvent in many of the preferred forms to provide good workable fluidity and to further effect a neat impregnation and hardening of the resin following a drying step or a curing step. The resin in the liquid composition may contain a chemical curing agent for the resin in many preferred forms, but

4 a chemical curing agent may not be necessary for many other forms.

Reference may be made to resin forms undergoing Idrying or hardening. These terms are used in an equivalent manner, and include the concepts of air-curing or curing .by chemical agents, catalysts, hardeners or the like. TheV term hard may be used more meaningfully relative to air curing. In any event, the terms are used equivalently to state that a resin in a liquid composition or liquid form is converted into a hard fllm or layer which is characteristic of resins which are conventionally air-cured or chemically cured.. Such terms will have limited meaning for materials which do not harden into a film, such as some organic solvents or plasticizers. When dealing with resins which are cured into a hard, dry iilm, the water treatment step is performed before the resin substantially cures, dries or hardens. When the liquid composition contains an organic solvent for the resin, the water treatment step is preferably made while the composition remains wet on the paper, that is, before all the solvent has been removed.

The amount of solvent which may be removed may be a major amount of more than 50% of the original amount and, say, less than about Opaque marks may be formed on a sheet of paper by a printing step where a liquid composition is printed as a wet film on the surface. This may be conventionally done by a hand stamp, an elastomeric die on a roller or by similar letter press techniques. While a printing step is a preferred form, the film of liquid composition may be applied otherwise as by brushing or spraying the liquid compositions through a stencil. Other methods of application will occur to practitioners in this art.

This paper may be made entirely opaque by dipping `the sheet in the liquid composition or by depositing a charge of the liquid composition on the surface of the 'paper and then pulling a roller or the like through the deposited charge until the entire surface is covered with a wet film of the liquid composition. Whatever the identity of the resin material which is deposited, it is preferred that the wet film undergo some drying before the water treatment step. A sheet of paper with the wet film may be passed, for example, over a hot felted drum dryer, for 60 seconds, said drum being held at 79 C.

The water treatment step may be performed in a variety ofv ways such as spraying, fogging, dipping, providing a high humidity environment, or by other means. A successful step provides for dipping the sheet of paper in a body of water, then nipping the paper between rollers to remove excess water, and then air drying or drying at moderate temperature levels. When using a plurality of successivel wetting and drying steps, the sheet .may be dipped in water and nipped between rollers, dried in an oven at temperatures of about C. or over a hot felted dryer held at 78-80 C., dipped again, nipped, dried again, and so on.

The dipping technique provides that the paper is immersed in the water, and then withdrawn without prolonged immersion. It is not known for certain to what degree the thermosetting resin film has dried or hardened during the plural execution of such successive steps. Clearly, it is preferred no t to encounter any undue delays between the successive steps butto repeat them as quickly as possible until the opaque area is desirably developed. In general, it is preferred that the first water treatment be applied after `about a minute or two following application of the liquid composition so that adequate impregnation occurs. The successive wetting step is preferably executed immediately following drying or substantial drying of. the. paper. Further wetting steps are likewise preferably executed immediately. following substantial drying.

Reference has been made and will be made to resins, and such term is intended to cover materials which can be applied as a wet film which can impregnate paper fibers or the paper web, and which materials can be contacted with one or more water treatments to increase the opacity of the resin-treated area. A sufficient number of water treatments are expected, in many cases, to lead to an opacity greater than that of the original paper. In some instances, this may not be attained practically with respect to the number of water steps required or the degree of opacity which is developed. The practitioner may readily determine, however, what is practicable for a particular application. The resins may include the natural resins which may be substituted or modified, such as rosin; hydrogenated methyl ester rosin; partially decarboxylated rosin; triethylene glycol ester of hydrogenated rosin, hydrogenated abietate esters with various mono, diand trialkyl glycols or mixtures thereof; and others. Natural resins may be combined with solvents or plasticizers to desirably attain an operable viscosity. The liquid composition may even be a softened solid such as Aquapel, an alkyl ketene dimer supplied by the Hercules Powder Co.

Other resins are various esters of polyols Iwith saturated diacids and unsaturated diacids. These may be polyesters of glycols 1with dicarboxylic acids which are saturated such as adipic, pimclic, and azelaic. They may also be glycols esterilied with unsaturated dicarboxylic acids such as succinic. Some representative esters are polypropylene adipate, triethylene glycol hydroabietate and the like. Other esters are dialkyl sulfosuccinates; sucrose acetate isobutyrate, and sucrose acetate butyrate as disclosed in U.S. 3,085,898 issued to the present assignee.

The resins may be used alone or in a mixture in the liquid composition. Thermosetting resins are successfully used, and representative resins of this type are disclosed in U.S. Letters Patent No. 3,140,050 issued to the present assignee. Such resins include the urea melamine formaldehydes, polyester, phenolic resins and epoxy resins, Other thermosetting resins are the alkoxy substituted melamine resins such as hexamethoxymethylmelamine. Such resins may be combined with a variety of organic solvents or plasticizers to effect the desired viscosity. Said solvents include ketones such as methyl isobutyl ketone; esters such as dibutyl phthalate; various alkylene glycol alkyl ethers such as ethyleneglycol monomethyl ether; and a large number of other solvents. Representa- `tive solvents and plasticizers are also listed in the foregoing U.S. Patent No. 3,140,959.

Chemical curing agents are preferably used for the foregoing thermosetting resins, and such agents are well Iknown in the art. While a preferred liquid composition vvould include a thermosetting resin, a solvent, and a curing agent, it should be noted that the solvent and curing agent may be omitted. Selected thermosetting resins or combinations of resins may be sufficiently liquid to be applied to the sheet of paper in the form of a design, and then be water contacted. Certain epoxy resins have been used successfully Without a curing agent. Certain epoxies have also been used successfully without a sol- .vent. Reference is likewise made to the foregoing U.S.

Patent No. 3,140,959.

The resin esters may also be polymeric plasticizers such as the plasticizer provided under the name of Eastman N.P. supplied by the Eastman Chemical Products Company. The Eastman plasticizer is derived from neopentyl glycol. Likewise, the ester may be a monomeric plasticizer used in conjunction Wtih some higher molecular Weight polyester to provide dilution or solvation. These plasticizers may include diesters of phthalic esters and lower monohydric alcohols, such as the dimethyl, di-

ethyl, or the like. Other plasticizers or solvent esters may include cyclohexanone. Such monomeric plasticizers, of course, are preferred as diluents for polyesters or other resins to effect the desired fluidity. A monomeric ester may, however, be useful for developing an opaque mark `by itself and one such ester is the monomeric epoxide supplied under the trademark Monoplex MS-73 by the Rohm and Haas Company.

Still other resins may be used such as aryl sulfonamides diluted with a plasticizer such as dioctyl phthalate. Thermoplastic resins also iind useful application in this invention, such as acrylonitrile butadiene styrene or ABS. It will be apparent that other thermoplastics may be of the allyl type, of the acrylic type, of the amide type, of the iluoro type, of the vinylchloride type, and still other types. Still other resins include the cellulosic such as acetate, propionate, or ethyl cellulose resins. Among other operable materials are film formers and paper impregnators such as triacetin, -diethyleneglycol monomethyl ether, and N methyl Z-pyrrolidone.

The opaque area may be formed on various paper, say from 9 pounds to 44 pounds. Such weights conventionally refer to a ream of 500 paper sheets, each having a dimension of 17 x 22". Greater paper weights may become eliminating factors by themselves because they transmit little light.

The opacity of the treated area increases in general about at least 1% relative to the original condition of light transmission. The opacity may increase to higher levels depending on the particular resins used in the liquid compositions. In any event, an increase of at least 1% results in a sufficiently observable opacity. The

^ opaque area also results in a measurable and definite rise Irelative to the original surface of the paper, and this rise may be determined by caliper measurements. The caliper rises by at least about 5% relative to the original thickness of the paper, but this may vary and include substantially higher levels. This again may be determined by the nature of the resin and the liquid composition.

Some examples are now presented, but they are intended to be only illustrative, even though they include embodiments now contemplated to best meet various purposes of the invention.

EXAMPLE 1 A liquid composition is prepared by mixing the following impregnating materials in the listed amounts:

Ingredients: Parts by weight Epoxy resin (Dow DER-332) 5 -Epoxy Hardener (Dow Experimental Hardener X-2654.4) a Methyl Carbitol (diethylene glycol monomethyl ether) 4.5

A small metered amount of liquid composition is deposited on the surface of a foot square piece of 1/2 thick plate glass. The composition is spread uniformly over the surface with a hand roll, consisting of an engraved roll bearing 75 depressions per inch and tted With a handle. A die or hand stamp of rubberlike material having inscribed on the face thereof a typical watermark design is rst pressed against the Wet lm of the composition on the glass and then stamped on a paper sheet. The sheet is dried in a hot air stream at about C. for about 30 seconds. The sheet of paper is then totally immersed in a bath of water maintained at room temperature. The sheet of paper is removed, the excess water is removed as by a nipping operation between a brass roller and a rubber covered roller, and the paper is then subjected to heating by hot air at about 105 C. for about 1 minute. The paper is reWetted in water and again dried as described. The procedure is repeated until a desirable opacity is obtained.

EXAMPLE 2 Ingredients: =Parts by weight Epoxy resin (Dow DER-332) 5 Pyromellitic dianhydride l Methyl Carbitol 41/2 The above liquid composition, with epoxy resin impregnating compound, is manipulated in the same Way described for Example 1 to obtain a shadow chemical watermark of desirable properties.

The pyromellitic dianhydride, which is supplied by the Du Pont Company, is a good curing agent or hardener for the epoxy resin'since likelihood of possible discoloration is even further reduced. The same property makes it a desirable curing agent also for translucent chemical watermarks.

It is intended that the water in the water treatment step may be present in mixtures, solutions, suspensions or the like. The use of the term water may be used interchangeably or in an equivalent manner with aqueous liquids.

Such aqueous liquids may particularly include sizing solutions. Such sizing solutions are commonly used in the paper art, and the most popular are starch solutions, such as the chlorinated and ethylated starches. Other sizing agents in water solutions may be used as aqueous liquids in the wetting step. The sizing solution may include a chlorinated starch and water solution which has been cooked for a sufficient time and at a suicient temperature to swell the starch granules to form the desired solution. The various starch concentrations in water may be maintained at moderate temperatures ranging from about room temperatures to about 150 F.

Such a sizing solution may be in a conventional size tub, and the paper web may be moved to such tub to complete the contact of the paper and the starch solution. Various equivalent means are known for sizing paper. In addition to the size tub, there are horizontal and vertical size presses of puddles, kiss coating and the like. The use of the term sizing is intended to refer to surface sizing rather than internal sizing. After the paper web has left the size tub, it may be nipped between rollers to remove the excess starch. The entire web of paper is therefore coated with a starch solution so that the paper is simultaneously sized and the impregnating resin is wetted with the starch sizing solution. This leads to an advantageous practice of the process because paper can be conventionally sized while at the same time executing a step which leads to opacifying the sheet or forming a shadow chemical watermark. While a plurality of successive sizing and drying steps may be used to enhance the development of the opaque area, it is preferred to employ a liquid composition and resin which can lead to an opaque area following one or two wetting steps with a sizing solution. It is not desirable to build up the starch on paper to undue levels which may possibly occur witha high number of successive starch sizing and drying steps. The paper wetted with this size solution may be dried in a variety of ways, such as by moving the web of paper over heated drier rolls maintained at temperatures below the level which would otherwise damage the paper. When using a sizing solution, the starch, or its equivalent ingredient, will be incorporated as a part of the opaque area.

The following example presents an embodiment to teach the formation of opaque areas with a sizing solution.

EXAMPLE 3 A liquid composition is prepared from the ingredients of Example 1 and treated `by similar process steps. However, the sheet of paper is totally immersed in a bath containing 8% chlorinated starch in water, said bath maintained at 80 F.1to 150 F. The sheet of paper is removed' and subjected to heating by hot air until the paper is dry. The paper is then rewetted and again dried as described in Example l.

The following example teaches the method of opacifying entire strips of paper. Such strips may be standardized and subjected to uniform testing procedures. While substantial data will be presented relative to such entirely opacied strips of paper, it should lbe understood that the same conclusions will operate relative to the preparation ofk shadowrnarks.

EXAMPLE 4 The following liquid compositions A and B are prepared.

Ingredient: n Parts by weight Epoxy resin, Dow 332 5 Curing agent, U.S. Borax 110 1 Methyl carbitol 5 Epoxy resin, Epon 812 6 `Curing agent, Epon H-3 3 Methyl carbitol 8 Strips of various paper Weight are provided in dimensions of 4% x 11". Some strips are dipped in composition A and others in B. The strips are then nipped between a brass roller and a rubber covered roller, and then passed over a hot felt drum dryer for seconds at 79 C. The strips were then treated with water, some of the strips being given one water treatment, others three, others six, others nine and others twelve water treatments. The strips are dipped in the water, npped between the described rollers and then dried by being passed twice over the felted drum for a total drying time of 120 seconds. This series of dipping, nipping and drying is followed for each additional Water treatment. Opacity measurements were made on control strips and on the water treated strips.

The following table lists the opacity measurements obtained with liquid impregnating compositions A and B. The opacity measurements represent the average of three readings on spaced portions of each strip, and they are collected with a Bausch & Lomb opacimeter, B & L Optical Co., Rochester, N.Y.

OPACITKIS WITH DIFFERENT PAPER WEIGHTS 9 lbs. 13 lbs. 20 lbs. 24 lbs. 28 lbs. 36 lbs.

Composition A:

12th water 7 58. 7 72. 0 82. 0v 87. 5 88. 8 92. 2

The liquid compositions may be used with paper which is either surface sized previously or not surface sized. An important advantage of the process is that non-surface sized paper may be simultaneously surface sized and rendered opaque. The opaque area, of course, may be limited as for a shadowmark, or may extend throughout theV entire surface of the `iinished paper sheet. Apreyiously sized paper will receive an additional sizing treatment which may be cumulative or complementary to an original sizing to obtain desired sizing properties.

The data of the foregoing table (composition A) lis utilized to graphically represent the difference in opacity following a plurality of water treatments. The data collected from 9 lb. to 36 lb.

shown in FIGURES 1 to 6. The increase in opacity is represented as being directly proportional to the number of water treatments. The

graph represents the difference between the opacity of the control or untreated paper strips an strips. The X axis of all the gures is divided by same number of units, but the unitary Epon curing agent H3 4 3 Methyl Carbitol 8 Y axis is varied to better depict the different measure- 10 ments.

EXAMPLE 5 A liquid composition is prepared from the following The epoxy resin and the curing agents are supplied by the Shell Chemical Company. The above liquid composition is applied t0 9 lb. and 20 lb. paper strips by following the process steps generally as disclosed in Example 4. Replicate runs of each paper weight is wetted, dried and rewetted in a series of twelve separate water treatment steps. The opacity of a blank paper is measured, and the treated areas are meausred after selected successive water treatments. The data of following Table II shows that the opacity of the treated area is increased with succes- 25 sive water treatments, and that the opacity of the 9 1b.

the 12th Percent (7)/(5) X100 paper is increased up to the 9th water treatment, whereupon it remains substantially unchanged up to water treatment.

ber of opaque The rethe area, while the rst water treatment was insufficient for this purpose.

TABLE I Second Percent water (1)-(2) (3)/(2)X100 treatment nating composition to obtain a replica num areas after one and after two water treatments. sults are p water treatment was suicient to opacity Blank TABLE II Paper Weight, lbs.

Avge.

Hexamethoxymeth Methyl Carbitol The above li Ingredients ble I-A which quid comp The same paper and process steps as in Example 5 are followed to obtain the data of following Ta shows that, in several instances, one water treatment was suicient to opacity the paper; and two Water treatments were adequate to opacity the papers in all instances.

TAB LE I-A Second Percent water Percent (1) (2) (3) [(2) X100 treatment (2) (5) (1)-(5) (7) /(5) X100 First water treatment Blank 139026265138928 LQWQLQQLLLAMLZZ.

1 l EXAMPLE s A liquid impregnating composition is prepared from the following ingredients and amounts:

TABLE V Paper Weight, lbs.

9 91 92 13 Ingredients: Parts by Welght Blank 52.2 523 53.8 @8 9 Epoxy resin, Dow 332 5 lstdwatr treatliienti ggg gf n Wa er trea men Curmg agent BoraX epoxy Cul-lng 3rd Water treatment 62.3 61.1 61.5 73.6

agent 110 l n watertrealmenl n u 1 bt water trea men Methyl Carbltol 4/2 6th Water treatmenl 75.? The epoxy resin is Obtained from the DOW Chemical io tt tl t:1113111113331121111.- 3?:5 Company and the curing agent from the U.S. Borax Ref lgltihwatr tiieatilnentE gl search Corporation. The above liquid composition is mh tfgtgt:j 7513 applied to 20 lb. and 9 lb. paper strips which are run 12th water treatment 75.0 throughf Successlve Senes of Wate treatment Steps m the 1 Each gure is an average of nine separate values, three measurements manner indicated in Example 4. Following Table lII shOWS 15 prfallllleh f ft t l th that the opacity is continuously increased with successive mentsacper allefs an average o een separa e Va ues ree measme' water treatments up to and including the 12th water treatment.

TABLE HI EXAMPLE 11 Paper welght'lbs A li uid irn iegnatin` composition is repared from q p e p 2o 9 the following ingredients and amounts stated.

Blank m; 22 Ingredients: Parts by Weight 84j .l 4715 25 Epoxy resin Iso Chem Res Trans Flex (Iso Chem tlti1 wetter treatlmen-.- Resin Company) l0 9t wa ertrea men 12th water treatment 85.7 56.2 FP1 Cure 877 1 r 3 Methyl Carbitol l0 The above liquid impregnating composition is applied EXAMPLE 9 30 to 9 and 2() lb. paper strips and the opacity of the area n n A liquid impregnating composition is prepared from befQfe al1d after treatment 1S measllled th1'0ugh-a SUC the following ingredients and amounts Stated; cessive series of water treatment steps by following the P t b .oh procedure of previous Example 4. Following Table VI Ingredlentsl 1 300 1500 ar s y Welnu; shows that the opacity measurement is continuously in- Polyesler resul; KOP ac D 2 35 creased to the 12th water treatment step on one 9 lb. enzy perold, 10 paper sample, and through the 4th water treatment step Met y1 Car o on the other 9 lb. sample. No further measurements were The polyester resin is obtained from Koppers Company, taken. The measured opacity is also continuously n- Inc. The liquid composition is applied to 9 and 20 lb. creased for the 20 lb. paper sample. paper strips which opacity is measured through a succes- 40 sive series of water treatment steps as described in preceding Example 4. Following Table IV shows that the opacity TABLE VI is continuously increased with successive water treatments as veried by selected opacity measurements. Paper Welght lbs' TABLE Iv Blank 54.0 53.6 82.9 1st Water treatment 41.8 40. 7 67. 2 Paper weight, lbs. 2nd Water treatment 49. 9 52.1 74. 8 3rd Water treatment 55.8 58. 5 79. 7 20 20 9 4th water treatment 58. 3 61. 9 82. 9 5th Water treatment 60.2 85. 5 Blank 83.8 83.0 55.4 6th water treatment 60.6 86.5 1st water treatment. 75, 0 80. 5 43. l 7th water treatment 62. 0 3rd Water treatment- 84, 3 84. 8 49. 3 9th Water treatment 63. 2 6th water treatment. 8F. 2 S4. 9 53. 8 10th water treatment 63.2 9th water treatment- S6. 0 85. 4 55. 4 11th Water treatment 63.9 12th water treatment 87, 0 56. 7 12th water treatment 65.3

1 Each figure is the average of sixteen separate values, three measurements per value. EXAMPLE 10 A liquid impregnating composition is prepared from the EXAMPLE 12 uollngt mgredlents and amounts Statesart by ight Eight impregnating liquid compositions, designated A gre le s: s We throu h H res ectivel are re ared-as follows' Hexarnethoxymethylmelamine, Cymel 301 l() g p y P P Curing agent, Epi-Cure 8771 3 Methyl Carbitol 2 Ll The hexmethorrymethylmelamine ls obtained frorifi the gosmon Ingredients American yanimid Company, and t e curing agent rom A Monomer X 970 (Rohm & Haas 0o.). Celanese Resms CmPany- The hquld compqsltlon 1s B Poly Glycol P-400, polypropylene glycol MW 400 applied to 9 and 13 lb. paper strips, and the opacity of the C Flowaglellegg D1 Vi 1 chlod (U D areas is measured throigl a Sueeesive serles lof Wtr D Fam arttsfnpmqtgliasan gimilcnfa ent t SCI-i e (3e in a e 0- ive pars *pocry 11, epoxy an acryic com inareafm T lsjleps ashde h u pre gfE mp 4 70 noniieliohem,0o.);tenpartsMethyiCarbitoi. Owing a de V S W t1 ;t t e Opalty 0 t tfaed area E Surfytnrl 485,1reatto`p prolliliet of lethyllei?i oxiide and is increase on t e paper t rougn t e r water aeeyeniesyeo f ire@ emiasan estes.

f P 40o, t treatment; and for the 13 lb. paper through the 11th water F sllol Chsrffnd glycol combmamn MW treatment. The opacity of the treated area after the 12th G Mehylarbitl- H Triprlpioniii.

Water treatment is not substantially altered.

3,486,923 13 14 Following Table VII shows the opacity measurements caliper is demonstrated following one or more water of the above eight liquid impregnating compositions which treatments. were applied in accordance with the procedures of EX- ample 4, all of which were used on 9 lb. paper. The data EXAMPLE 14 shows that for compositions A through D, inclusive, the

opacities have been uniformly increased relative to the 5 A variety of liquid impregnating compositions were s blank opacity by the 5th water treatment. For liquid imprepared, and paper strips are dipped in each liquid cornpregnating compositionsEthrough H, inclusive, the opaciposition. Different sets of strips were given a diierent ties have been all increased relative to the blank by the number of water treatment steps-from one to twelve suc- 6th water treatment. Such increase, in general, has concessive water treatments with intervening drying steps tinued with successive water treatments except for com- 10 generally as described in Example 4. The various formulapositions E and H which show some slight reductions in tions are identified below in Table IX, and the supplier opacity by the 12th treatment. is indicated in parenthesis next to the ingredient. The re- TALBLE VII Liquid compositions A B C D E F G H Blank 54.3 54.3 54.3 54.8 54 3 53.8 549 54 2 istwater treatment 42.4 32.8 29.8 42.9 57 6 42.7 55.8 28 6 2nd water treatment 55.1 43.5 37.3 48.6 3rd water treatment 55.5 50.2 49.2 51.9 58 3 49 56.6 47 4 4th water treatment.. 52.4 49.3 61.1 54.7 5th water treatment 55.5 54.5 62.7 55.0 6th water meeneem 57. 5 57. 1 55. 9 54. 0 9th water treatment 59.1 58.6 56.0 61.5 12th water treatment 58. 7 64. 0 56. 8 56. 8

EXAMPLE 13 30 corded opacity measurements are presented in following A liquid impregnating composition is prepared from Table X' the following ingredients in the amounts listed.

TABLE IX Ingredient: Parts by weight N Im Polyvinyl chloride (Marvinol) V2 35 o' pregna mg mammal Solvent Tripropronin plasticizer 10 880 5 izgtsuEpocryi resin E-ii 10 parts Methyl carbiiei.

e A number of Paper Strips are dipped in Water, Dipped 879 5 parts Morester X-973 (Pzer) 10 p arts Kodaex Tn'proand dried according t0 the procedures described in EX- 882 Dresinol S1621 (Shen) Ploumample 4. Some of the strips have only one water treatment, 901 5 PalVtS b2 @WMM/Kane dim' 5 Parts Methyl Carbitol boxylic anhydride (Matheson, and others have three, six, nine and twelve successive 40 coremangzeu), water treatments. Paper strips of varying weight are given 906 Gigef E510 (General the same treatments, and the opacity and caliper readings 911 Methyl oe'rbirei (Union ar are reported as average of three readings on spaced por 907 N Methy1 2 1,yrrohdoue (Gem tions of each strip. Such averages are listed in following Anii'me).

908. Stab-U-Cel (Upson Chem.) Table VIII. The caliper readings are in mils and rare 45 919 L 5310 (Union Carbide) organ0 ,obtained with a TMI micrometer, Model 549M, Testing siiieene eepeiymer.

932. O.T. (Amer. Cyanamid) dioc- Machiiies, Inc., Mineola, Long Island, Each capiler me Sodium sulfosucciatevalue is the average of three separate readings on spaced portions of each strip.v

TABLE VIII sib. 13 ib. 20115. 24115. 28 1b. 3611 Opacity Caliper Opacity Caliper Opacity Caliper Opacity Caliper Opacity Caliper Opacity Caliper 54. i. 9 69. 0 2. 9 82. 5 4.5 87. 3 5. 5 85. 5. 2 9i. 6. 9 60.0 1.9 72.4 3.1 83.2 5.2 88.0 6.8 86.2 6.0 91.8 7.5 58.9 2.1 74.4 8.1 85.0 5.0 89.5 6.8 87.5 5.8 92.1 7.5 56.3 1.9 73.8 3.1 85.7 4.9 89.7 6.0 88.1 5.7 92.2 7.9 55.8 1.9 73.5 3.1 85.2 4.9 89.3 6.0 88.5 5.7 92.3 8.5 53.2 1.8 73.0 3.0 85.5 4.8 89.0 5.8 88.0 5.6 91.8 7. 5

- The data of the foregoing Table VIII shows that the The Dresinol material is a partially decarboxylated opacity is not, for the most part, substantially changed pale rosin; Morester X-973 is a saturated polyester; and with water treatments in excess of one. The increase in the 'Silicone L-53l0 is an organo-silicone copolymer.

TABLE X 1 5 The data in foregoing Table X shows that water treatment leads to opacity with a wide variety of resin materials which can form wet films on paper and which can impregnate the paper. The data further shows the advantage of using a plurality of water treatments to develop or enhance the development of a desired opacity.

EXAMPLE l5 A liquid impregnating composition is prepared from an alkyl ketene dimer supplied by the Hercules Chemical Co. under the trademark, Aquapel. The resin is heated until it liquifys at about 120 F. The process steps of Example 4 are then followed by using two water treatment steps to obtain an opaque area. The opacity of the heated area increases upon standing.

EXAMPLE 16 A liquid impregnating composition of Silicone L-5310 is used to impregnate entire strips by the procedure described in Example 4, Another liquid composition of Surfynol 485 is used to impregnate other strips of the same paper. Some of the strips are given a plurality of water treatments by following the method of dipping, nipping and drying as described in Example 4, and other strips are given a plurality of prolonged water treatments of three minutes per treatment. Still others are given a plurality of prolonged water treatments of varying immersion times. The results are shown in the following Table XI.

TABLE XI Treatment Silicone opacity Surfynol opacity The data indicates that prolonged water treatment may be the equivalent of a plurality of water dip treatments, but preferred results may still be obtained with the plurality of dip treatments.

EXAMPLE 17 Paper strips of the type described in Example 4 are dipped in a liquid impregnating composition of N methyl- Z-pyrrolidone. The strips are nipped and then passed twice over a hot felted drum dryer at 60 seconds a pass. Opacity developed during the drying treatment, that is, even before the iirst water treatment. Following water treatments enhance the development of the opaque area.

Paper articles of this invention have opaque areas which may have some variance relative to their permanence and serviceability and color. The art may very well accept certain paper articles with opaque areas which have a permanency and serviceability less than that of the paper itself. But, in general, many paper articles are obtained in which the opaque area is serviceable towards receiving writing and printing and is substantially permanent as the paper itself. The attribute of permanency would include substantial resistance of the opaque area to mechanical abrasion encountered by means such as erasing. The attribute of serviceability would include a resistance to discoloration for at least desirable periods of time.

The useful life of the paper may be variously measured, and the substantial majority of stationery bond, for example, has a relatively short, useful life. Nonetheless, the shadow-marks and opacity on such bond papel would retain the desirable properties, in most instances, even after the stationery bond has been stored or iiled for substantial periods.

Methods for making the paper articles of this invention can include the batch or continuous processing. The continuous process will be preferred for a large scale production wherein a run of paper web will move through appropriate stations. A marking station would contain the liquid composition and the paper web would receive the conguration of the marking formulation or be entirely covered at such a station. The running web would then pass through an aqueous station where contact would be made with the aqueous liquid before the resin in the liquid composition hardens or dries. The paper web leaving the iirst water station would then be passed through succeeding stations for drying and wetting the papers to effect a successive number of drying and wetting steps, if desired. The paper web could then be severed at a cutting station into selected dimensions or be otherwise handled.

What is claimed is:

1. A method for opacifying areas on paper which comprises,

applying a non-aqueous liquid composition to the surface of said paper, said composition including a resin, said resin capable of being laid down as a wet iilm and impregnatin-g the paper,

contacting said resin with Water, and

drying said contacted surface by application of heat,

and the opaque area on the paper is developed by repeating a suicient number of successive water contacting and drying steps until the opaque area is desirably formed.

2. A method for opacifying areas on paper which comprises,

applying a non-aqueous liquid composition to the surface of said paper, said composition including a resin, said resin capable of being laid down as a wet lrn and impregnating the paper,

contacting said resin with water in the absence of a sizing agent, and

drying said contacted surface.

3. A method as in claim 2 wherein the liquid composition is applied to a limited surface area of a sheet of paper in a selected design, and

at least that limited portion is then contacted with said water to obtain a shadowmark.

4. A method as in claim 2 in which the entire surface of a sheet of paper is contacted with the liquid composition to obtain an opacied sheet of paper.

5. A method as in claim 2 wherein said liquid composition has a viscosity sufficiently high to retain the applied design configuration, but suiciently low to permit impregnation of the paper.

6. A method as in claim 2 in which said selected design is printed on a limited surface area of the sheet of paper so that a film of the liquid composition is laid down in the selected design, and said film being sufficient to impregnate the paper while still retaining the configuration of the selected design.

7. A method as in claim 2 in which the liquid composition includes an organic solvent in which the resin is soluble.

8. A method as in claim 2 in which the liquid composition includes a chemical curing agent for said resin.

9. A method as in claim 2 wherein the resin is a material convertible to a hard iilm by curing, and wherein the step of water contact is effected before the resin substantially hardens.

10. A method as in claim 2 wherein the resin material is of the class of tripropionin, N methyl 2-pyrrolidone and diethylene glycol monomethyl ether.

11. A method as in claim 2 wherein the resin is a polypropylene glycol having a molecular weight of about 400.

12. A method as in claim 2 wherein the resin is an alkyl ketene dimer.

13. A method as in claim 2 wherein the resin is a mixture of an epoxy and an acrylic resin.

14. A method as in claim 2 wherein the resin is a mixture of ethylene glycol and acetylinic glycol.

15. A method as in claim 2 wherein the resin is a polyvinyl chloride.

16. A method as in claim 2 wherein the resin is a dicarboxylic anhydride plasticizer.

17. A method as in claim 2 wherein the resin is an organo-silicone copolymer.

18. A method as in claim 2 wherein the resin is a saturated polyester,

19. A method as in claim 2 wherein the resin is of the class of a natural resin, a substituted resin and a modiiied resin.

20. A method as in claim 2 in which the resin is an ester of a polyol and a saturated diacid.

21. A method as in claim 2 wherein the resin is a cyclohexanone.

22. A method as in claim 2 in which the liquid composition includes a thermosetting resin of the class of an epoxy,

a polyester,

an alkoxy substituted melamine,

a urea formaldehyde, and

a melamine formaldehyde.

23. A method as in claim 22 in which the liquid composition is substantially free of a chemical curing agent for said thermosetting resin.

24. A method as in claim 22 in which the liquid composition includes a chemical curing agent for said thermosetting resin.

25. A paper article made by the method of claim 2.

References Cited UNITED STATES PATENTS 2,933,416 4/1960 Haakh et al. 117-63 3,140,959 7/1964 Vaurio 117-38 3,288,628 11/1966 Schur et al. 117-38 3,293,062 12/1966 Skofronick et al. 117-155 X RALPH S. KENDALL, Primary Examiner A. M. GRIMALDI, Assistant Examiner U.S. Cl. X.R. 

